The as yet unnamed series takes place thousands of years before the events in Game Of Thrones, with HBO saying it “chronicles the world’s descent from the Age Of Heroes into its darkest hour”.Other newly announced additions are Sheila Atim, Ivanno Jeremiah, Georgie Henley, Alex Sharp and Toby Regbo, and British director SJ Clarkson has been confirmed to lead the pilot episode.

Fans are advised to forget any preconceived ideas, with this message in a HBO teaser: “From the horrifying secrets of Westeros’s history to the true origin of the White Walkers, the mysteries of the East to the Starks of legend, only one thing is for sure: it’s not the story we think we know.”